Collective motion is a ubiquitous phenomenon in many biological and social systems including bacteria [1]}, animals [2]}, and humans [3]}. Over the past two decades, substantial research has been devoted to the understanding of human movement, thanks in part to the availability of large-scale human mobility data collected by a broad range of new technologies including banknote circulation [4]}, mobile-phone records [5]}, [6]}, [7]}, Bluetooth scanning [8]} and GPS tracking [9]}, [10]}. Initial empirical observations suggest that human movement at the population level satisfies a generalized continuous-time random walk [4]}, while later work shows that individuals’ mobility patterns are better captured by a more sophisticated exploration and preferential return mechanism [6]}. However, these empirical studies focus mainly on the asymptotic behavior of moving individuals; little emphasis is placed on social interaction among them.
